It is known in the art to control machine tools, such as lathes for example, by a computerized numerical control (CNC). In this respect, a CNC machine tool may be operated automatically, i.e., without interference or input from an operator, or in the alternative, the machine tool may be provided with a control device enabling control of elements of the machine tool by an operator. For example, an operator may perform manual turning operations on a workpiece held on a headstock chuck of a lathe.
In general, a lathe has at least two slidable carriages acting mutually orthogonally, i.e., in directions perpendicular to one another, and conventionally, a manually operable control device is fixed to the longitudinally movable carriage for control thereof and movement therewith. However, since this control device moves with the carriage, the speed of traverse or movement of the carriage is often limited to avoid the risk of injury arising if the control device were to collide with the operator's body. Indeed, in some countries the speed of movement of the longitudinally movable carriage is restricted to a few meters per minute to prevent any such accidents from occurring. Obviously, it is drawback that production speeds are reduced whenever a limitation on the carriage speed is enforced or maintained.